The BRADLEY DEPARTMENT of ELECTRICAL and COMPUTER ENGINEERING

Power Electronics Systems Research | ECE | Virginia Tech

Research Areas

Power electronics research advances the technology for energy conversion. Virginia Tech has the largest university-based power electronics research program in the country. The Center for Power Electronics Systems (CPES) is a former NSF Engineering Research Center and has more than 70 industry partners. The Future Energy Electronics Center (FEEC) is noted for its technology for PV and EV inverters that achieve greater than 99 percent peak efficiency.

Current Research

Nanogrids

ECE teams are developing pre-competitive technologies to address the challenges in renewable energy and storage systems in the electric grid. Efforts are split into three issues: dc-nanogrid operation and performance, modular multilevel converters, and applications for enhanced grid performance and integration.

To boost dc-nanogrid performance, we are concentrating on developing bidirectional ac-dc nanogrid-interface converters, battery, PV- and wind-interface converters, and power management strategies. Multi-level converter efforts include SiC-based power Electronic Building Blocks (PEBB), SiC-based high frequency dc/dc transformers, 3-level bidirectional ac/dc nanogrid-interface converter, and harmonic/EMI filter design.

For enhanced grid performance, we are pursuing a hierarchical network of dynamically-decoupled sub networks, power sharing, and use of power electronics converters at the distribution and transmission levels.

High-density integration

Improving power density is an ongoing effort in power electronics. We are pursuing two paths, leveraging WBG power semiconductors and high-temperature passive components and ancillary functions. Both the switching frequency and maximum component temperature are pushed as high as possible, with frequencies beyond 5 MHz and temperatures above 200 C. Higher operating temperatures and increased power density enable the use of electronics in harsh environments.

We are currently pursuing integration technologies such as a die attachment on copper by sintering of nano silver paste and the development of magnetic materials for high-frequency conversion and EMI containment.

For components, we are developing low-profile magnetic substrates and magnetic structures with high energy density. We are also characterizing and modeling WBG devices. Module and system-level integration are also critical.

Wide bandgap power devices

ECE researchers are developing high-efficiency, high-power density switch-mode power supplies based on recent developments in Wide-BandGap (WBG) power devices, such as gallium-nitride (GaN) devices and silicon carbide (SiC) devices.

This technology is being applied to the Department of Energy PowerAmerica program. CPES is a partner in the multi-industry, multi-university program and is working with the WBG manufacturing industry to explore potential applications and impacts of the technology.

GaN research is using several testbeds, including a high-frequency adapter with 26 W/in3 power density and greater than 93 percent efficiency; high-frequency 1-3 kW off-line distributed power systems with 200 to 300 W/in3 power density and above 96 percent efficiency; and high-frequency 6.6 kW bidirectional on-board charger for plug-in electric vehicles with 95 percent efficiency and 30-50 percent volume reduction.

Electromagnetic Railgun

Virginia Tech's Energy Conversion Systems Laboratory (ECSL) has been working with the Naval Surface Warfare Center at Dahlgren to design, construct, and perform research on an electromagnetic launcher.

This reduced scale railgun is now fully operational, features programmable acceleration, and can serve as a testbed for new technologies for the Navy's full-scale railgun.

The high voltage pulse forming network (PFN) is comprised of several custom-built pulsed-power modules and has an overall capacity of over 1,000,000A. Advanced safety features and sophisticated controls via optic fiber are made possible by several microprocessors.

This program is a part of NAVSEA's Naval Engineering Education Consortium (NEEC) that aims to develop a future workforce for the Navy through interdisciplinary university research.